The modem circuit of a mobile communication device enables the transfer of digital data, which is to say bits or bit sequences, via a wireless connection by impressing the data on a carrier signal, having an established carrier frequency, during transmission by modulation or by extracting the data during reception therefrom by demodulation. Depending on the design of the modem circuit, a different transfer rate results during the transfer of the digital data. For example, the modem circuit establishes the form in which the digital data is transferred by way of quadrature amplitude modulation (QAM) and/or how many channels having differing carrier frequencies can be bundled for the transfer. A description of such a modem circuit is known from KR20090061224A, for example.
Since the operation of modem circuits requires electrical energy, these are generally deactivated in parked motor vehicles. As a result, however, the motor vehicle can no longer be reached from the outside via a wireless connection, for example for a software update of control devices of the motor vehicle. It is known from KR20160046191A in this regard to continue operating a modem circuit as a function of the state of the vehicle battery when a motor vehicle is parked.
It is known from KR20070006139A to cyclically activate a modem circuit, while an internal combustion engine of a motor vehicle is shut off. In this way, it is possible to re-establish a wireless connection to the motor vehicle at predetermined time intervals.
If the wireless connection is weak, a base station can transmit a control signal to a mobile communication device causing the mobile communication device to amplify the transmission signal thereof, which also increases the transmission range.
A method is known from US 2015/0222553 A1 for transferring mobile communication data to a motor vehicle over different data channels. The data to be transferred is divided among the different channels using so-called traffic shaping so as not to block the data requiring the highest transfer rate with low priority data. The different channels can be provided by simultaneously providing different wireless connections or reserving multiple channels in an existing wireless connection.
A method is known from US 2007/0190950 A1 for being able to transmit both speech and data via a voice channel of a mobile communication device so that it is also possible to transfer device data in a call center during a call. So as to achieve the greatest possible bandwidth for the voice channel used, corresponding check bits are used during the establishment of the mobile communication link. The data rate is defined for an existing wireless connection, which is required to establish the voice channel to begin with. The data rate is varied by adapting the encoding of the speech.